1. Field of the Invention
The field of art to which this invention pertains is the catalytic hydrocracking of hydrocarbons. This invention also relates to hydrocarbon conversion catalysts and their methods of manufacture. The catalyst composite of the present invention demonstrates unexpected and exceptional activity, selectivity and resistance to deactivation when employed in a hydrocracking conversion process.
2. Description of the Background Information
The hydrocracking of hydrocarbons by catalytic means is old and well known in the prior art. Hydrocracking of hydrocarbon oil, which may be high-boiling fractions, such as, for example, reduced crudes, gas oils, topped crudes, shale oil, coal extract and tar sand extract, generally is performed at relatively high temperatures and pressures of the order to 500.degree. F. and 500 psig and upward. Catalysts for the hydrocracking of hydrocarbons are generally moderate to strong hydrogenation catalysts.
The prior art hydrocracking catalysts will typically comprise one or more components selected from silica, alumina, silica-alumina, crystalline aluminosilicate, or other refractory inorganic oxide and at least one metal component from Group VIB or Group VIII. One or more hydrogenation components have been selected by the prior art to serve as the hydrogenation component in hydroconversion catalysts. The prior art has broadly taught that hydrogenation components may be selected from at least one of the following metals: iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium, platinum, chromium, molybdenum, tungsten, vanadium, niobium, and tantalum. See, for instance, U.S. Pat. No. 3,442,821 (Hilfman), U.S. Pat. No. 3,931,048 (Hilfman), and U.S. Pat. No. 4,040,979 (Gembicki et al.) which all disclose the use of silica-alumina carrier materials in connection with the hydrocracking process.
U.S. Pat. No. 2,270,812, Melaven, discloses a cracking catalyst (catalytic cracking in contradistinction to hydrocracking) consisting of a silica gel which has a thorium compound absorbed upon it in a layer not more than one molecule thick. The cracking process disclosed in that patent is preferably carried out at atmospheric pressure and may be carried out at 100 to 200 psig.
U.S. Pat. No. 2,723,243, Holden, discloses a cogelled silica-metal oxide catalyst primarily useful for cracking reactions. The metal oxides that may be composited with the silica include those of aluminum, magnesium, zirconium, beryllium, vanadium, thorium, and tantalum. The cracking reactions contemplated in that patent are carried out at 700.degree. to 1200.degree. F. and a pressure of from atmospheric to 1000 psig or more.
U.S. Pat. No. 2,532,497, Hoekstra, likewise discloses silica-metal oxide composites that are particularly suitable for catalytic cracking reactions, which generally are effected at a temperature of from about 800.degree. to about 1100.degree. F. at superatmospheric pressures ranging from atmospheric to about 50 pounds or more per square inch. Catalytic dehydrogenation is generally effected at a temperature of from about 900.degree. to about 1200.degree. F., either in the presence or absence of hydrogen and generally at pressures below 100 pounds per square inch. Reforming of gasoline to improve its antiknock properties is generally effected at temperatures within this range but at pressures of from about 100 to 500 pounds per square inch.
The present invention involves the discovery that the use of a particular cogelled silica-thoria catalyst comprising nickel and tungsten exhibits improved and unexpected hydrocracking conversion characteristics, such as, activity and selectivity, and stability.